Process for use of spent fischertropsch catalyst for manufacture of carbon monoxide-hydrogen synthesis gas



y May 27, 1952 B. J. MAYLAND PROCESS FOR USE OF SPENT FISCHER-TROPSCH CATALYST FOR MANUFACTURE OF CARBON MONOXIDE-l-IYDROGEN SYNTHESIS GAS Filed Dec. 20, 1948 SVS BNOZ NOLLSOEWOD FRESH STEAM FRESH CATALYST :moz Noliovaa NouvaaNaoz-m SISBHLNAS E Y GNV Hasdoal oNlzlNoeev/oao -HI-IHDSM E i WVBLS 4 (I) N O l n U. v JNVENTOR. 8 QNISBBOOZNOD 5J. MAYLAND l l BY I l @my @f 7&7

A T TORNEI/S Patented May 2.7, 1952 UNITED STATES TENT OFFICE PROCESS'FOR USE OF YSPENT FISCHER- TROPSCH CATALYST FOR `MAN-UFACf TURE F CARBON MGNOXIDE-HY- DROGEN SYNTHESIS GAS Bertrand J. Mayland, Bartlesville, Okla., aSSgllQiI to Phillips Petroleum Company, a corporation' of Delaware Application December zo, 1 948, se,ria1,No.ss,3e5

Fischer and Tropsch. -They discovered that'hyv drocarbons `may be made by reacting carbon monoxide with hydrogen over suitable catalysts and; under certainconditions. An inherent result of this processas practiced vtoday usinganiron catalyst is the formation of carbonon the catalyst. In time, due to the carbon and Wax depositions, the catalyst becomes less Vand less active, and must `have these deposits periodically removed -invsuitable regeneration means. This Vhas beendone in a number of different ways, `many of them comprising vburning -the deposits oi by combustion with an oxygen contaiing'gas.

It is an -object of this invention to provide a process for utilizing` spent Fischer-Tropsch catalyst for the manufacture of carbon monoxide and hydrogen synthesis gas.

' `Another object of `this invention is Y'to j provide a processior 'the manufacture of :carbon monoxide and hydrogen synthesis gas by utilizing a spent Fischer-Tropsoh catalystwhich has become at least partiallyvinactive due to the wax` and carbon ,depositions` thereon. Y

Another objectof this invention is to provide a process for the manufacture of carbon monoxide-hydrogen synthesis gas bythe iron loxidenatural gas reaction utilizinga spent Fischer.- Tropsch catalyst and .thereby regenerating the spent catalyst.

Further objects and advantages of this invention will be apparent to one skilled in the art from the-accompanying disclosure .and discussion.

I have discovered that a spent'lischer-Tropsch catalyst maybe used in such .a manner that in one step it "furnishes carbon to a 'process for the manufactureV of carbon monoxide and hydrogen synthesisgasand in a second step, furnishes oxygen to a natural gas oxidation for producing synthesis gas. Catalysts which are adaptable to my process are those, which are well known to those skilled 'in 'the vvart, containing iron, cobalt; nickel; andv the' `iure.' 'withircn r'being' usually preferred;

In accordancewith my ini/chum@ Spentfflllely divided Fischer-IIropSch catalyst which. hasbuilt. up a carbon depositand. whose eiiiciency for coriversion of carbon ,monoxide and .hydrogen tothe desired productshas fallen o'i, is utilized to produce carbon monoxide .andhydrogen synthesis gas. I have Vfound that a Fischer-Tropschcatar 1yst, particularly reduced iron, may retain 'a greatdeal of activity Whichis merely .blanketed.` so t0 Speakjmy the.y .carbondellosits and by and the like. I t is not .infrequent tov dnd such catalysts Whichhave as much as, 5.0. 4.volume 'per cent of carbon depositedthereon. Because; this catalyst still retains ay ereatdealc'ofyiits attirtv.A

it is economically desirable to regenerate the catalyst by reiniovins the `delfbsited carbon and other materials whichhave redlicedv its eiiciency. in conventional regenerationgprocesses'; wherethe deposits are merely burnedoihthere 'a danger of overheating thecatalyst particles 'and causing fusion because of lthe'heat generated Vin `burning' oi the carbon andjoxidizing thereduced iron.

According to La' preferrediembodiment of my process, a spent-`Irischer-'Ircps ch catalyst is passed `to a decarbonizing'andV regenerating zone along with Vcatalyst `from an -iron 'oxide-natural gas reaction, similarto that disclosed'inrnycopending application, Serial No; 49,826, i-led-Sep tember 17, 1948, which reaction has obtained its iron oxide from a Fischer-Tropsch synthesis process, JWhereit iscontacted with steam `and hydrogen at aniaverage temperature level of -1100 to 1200i F.,1thus removing vtheinaterials lWhich have reduced its eiiiciency andfforrning carbon monoxide, carbon dioxide/andhydrogen. Since the steam-carbon reaction 'proceeds fairly rapidly at temperatures as low as 1l00F.,:suirlcient heat is available to 4complete theremoval of the-car bon. Thelheat for vthe reaction is-suppliediby the catalyst from the ironfzoxde natural gasreaction whichi may `.take place atY temperatures" in the range of 1,40() to ,2D0Q9;F. The catalystmay be removed from itsreactoll Zone at a tempera--A ture withinrthe aboverreactiou temperature-range and it is Often desirable to withdraw it at a tenilactante-111A the. neehborbofid of 1600pr F.- .This catalyst is `,then Lcooled by lthe'stearn reaction while the catalyst from the Eischer-Tropsch syn thesis is heated, theaverage. temperature being about 1100to 1200 F. kThe product gases from the decarbonizing step in Awhich the reducedfirqn catalyst from the Fischer-TrOlQsch synthesis' ijs' oxidized, are utilized as supplemental' synthesis gas for the. hydrocarbon Sclll'il-hisis,process;i

The aecarbonized catalyst Vwhichhas been par;

tial-ly oxidized lis next treated with fresh steam.'

Because the oxidation of reduced iron proceeds at high rates in the presence of steam at temperatures as loW as 800 F., the iron can be reoxidized at least partially by continued contact with steam until the temperature drops below 900 F. The sensible heat of the iron oxide is utilized to superheat the steam which is then used in the decarbonizing zone. The reaction is very mildly exothermic and will furnish only a portion of the heat required, thus the remaining heat is supplied when the catalyst is cooled from about 1200 to about 900 F. Hydrogen liberated in this step passes along with the steam to the decarbonizing and regenerating step where it aids in removing wax deposits from the catalyst which is a conventional process and Where it may be incorporated with the synthesis gas produced in that step.

A portion of the catalyst which has been decarbonized and contacted with fresh steam is passed to a reducing step wherein it is prepared for re-use in the Fischer-Tropsch synthesis of hydrocarbons by any conventional means such as passing hydrogen through it at an elevated temperature. This freshly reduced catalyst is added to the Fischer-Tropsch reaction as spent catalyst is withdrawn.

The remaining portion of the fresh-steam treated catalyst is passed to a nal catalyst regenerating and preheating zone where it is contacted with hot combustion gases containing an excess of oxygen usually in the form of air. In this zone the catalyst is completely oxidized to iron oxide and preheated to a temperature in the range of 2300 to 2800o F. This catalyst is passed to a natural gas-iron oxide zone where the natural gas is converted to carbon monoxide and hydrogen in a preferred mol ratio of hydrogen to carbon monoxide of 1.7:1 to 2.311 by combining with the oxygen of the iron oxide. Some cracking of the natural gas takes place depositing carbon on the catalyst, or as it might be called, oxygen donor. From here on the cycle repeats itself. The catalyst from this synthesis gas producing zone and from the hydrocarbon synthesis zone containing carbon deposits are passed to thev decarbonizing zone and treated as hereinabove described.

It is advantageous to carry out the process of my invention in a fluidized phase,vthat is, maintaining the solid particles of catalyst in a highly turbulent state by passing a gas therethrough, because the nely divided Fischer-Tropsch catalyst may be most easily handled in this manner and because better conversion in the synthesis step and better contact in all the steps of the process are obtained. It is also of advantage to utilize iluidized phase operation because it is more easily maintained continuous and requires less equipment per unit quantity of product.

A clear understanding of some of the many aspects of my invention may be had by referring to the attached drawing, which is a schematic flow diagram, in conjunction with the following discussion. Various additional valves, pumps, and other conventional equipment, necessary for the practice of this invention will be familialto one skilled in the art and have been omitted from the drawing for the sake of clarity. The description of the drawing provides one method of operating my process; however, while this is representative in general of my process, various minor changes vmay be made in adapting the process to the various conditions within the scope of the invention. The following discussion will also serve to exemplify my invention.

Spent Fischer-Tropsch catalyst is passed through line I!! to steam decarbonizing and regenerating zone II. The carbon deposited on the catalyst along with other contaminating materials, such as wax and the like, are reacted with steam and hydrogen from zone I4, hereinafter described, at a temperature in the range of 1100 to 1250u F. and preferably in the range of 1150 to 1200 F. to form carbon monoxide, carbon dioxide, hydrogen, and steam. These products are removed from zone Ii via line I2 and passed to a Fischer-Tropsch synthesis unit hereinafter discussed. Below 1100 F. the reaction rate becomes too slow, however, in order to furnish the heat of reaction from the sensible heat of the recycled catalyst in line 32, the temperature should be as low as possible. These factors fix the temperature within the above stated preferred range. The decarbonized catalyst, which is also partially oxidized, is passed via line I3 to catalyst oxidizing zone I4 where it is contacted with fresh steam introduced thereto via line I6. Temperatures within zone I4 are maintained in a range of 800 to 1000 F. The olf gas from zone I4 is removed via line I5 and passed to zone II. Oxidized catalyst is removed from zone I4 via line Il. A portion of this catalyst is passed via line I8 to catalyst regeneration and preheating zone I9. Natural gas and excess oxygen are introduced via lines 25 and 20 to combustion zone 2i where they are burned to provide heat and oxygen for treatment of the catalyst in zone I9. The hot combustion gases are passed via line 22 to the regeneration and preheating zone. In this zone, the catalyst is completely oxidized to iron oxide and is preheated to a temperature in the range of 2300 to 2800 F. Usually, however, it is preferred to heat the iron oxide to a temperature in the range of 2300 to 2-500 F. because temperatures around 2800" F. may cause fusing. Cooled combustion gas is removed from zone I9 via line 23. Regenerated and heated catalyst is then passed from zone I0 via line 24 to synthesis gas production zone 26 where the natural eas or other hydrocarbon material introduced via line 21 is oxidized to carbon monoxide and hydrogen by the iron oxide at a temperature in the range of 1500fto 2000 F., but preferably in the range of 1550 to 1700 F. Carbon monoxide and hydrogen synthesis gas produced in zone 25 preferably in a mol ratio of hydrogen to carbon monoxide in the range of 1.7:1 to 2.3:1 is passed therefrom via lines 28, 29, and 30 to Fischer- Tropsch synthesis reaction zone 3l. Reduced iron oxide from zone 26 is passed via line 32 to line I0 through which it is passed along with spent catalyst from zone SI to steam decarbonizing and regenerating zone I l.

The remaining portion of catalyst removed from zone I4 via line l1 is passed through line 33 to catalyst sizing zone 3d where nes and agglomerated particles may be removed via line 36. From zone 34, the catalyst is passed via line 3l to catalyst reducing zone 38. The catalyst in zone 38 may be reduced by any suitable means such as are well known to those skilled in the art; for example, by use of hot hydrogen, for use in the Fischer-Tropsch synthesis reaction. The catalyst, after reduction, is passed via line 39 to Fischer-Tropsch synthesis reaction zone 3i. Fresh makeup catalyst may be introduced to zone 3i via lines lland 39. Products from zone 3l are removed via line 42 and passed to separa` tion zone v43 'where the tail gas -is removed for recycle via lines 29 and 30 to zone 3l. Separation zone 43 may be any suitable separation means such as a ash chamber, an accumulator, or the like. Product materials are' removed from zone 43 via line 44. Synthesis gas produced in the steam decarbonizing and regenerating zone Il along with the hydrogen produced in the catalyst oxidizing zone I4 is passed from zone H via line I2 to condensing zone 45 where steam is condensed to water and removed through line tl. The remaining synthesis gas, which may alsov contain some carbon dioxide, is passed Via lines 48 and 3|].to the previously discussed Fischer- Tropsch synthesis reaction zone 3|.

The various treatments involving iron oxide and reduced iron oxide take place preferably at about atmospheric pressure, although higher or lower pressures may be used. Space velocities range from 300-3000 volume of gas per volume of iron or iron compound per hour.

The spent Fischer-Tropsch catalyst as used in my process may have the same activity as the catalyst which remains in the Fischer-Tropsch reaction zone. However, to maintain a particular level ci catalyst activity and a continuous process a portion of the catalyst must be continually removed from the reaction zone while fresh regenerated catalyst is introduced thereto.

Advantages of my invention are many. Complete use of a Fischer-Tropsch catalyst is made, in that, even during the regeneration step, it is producing useful materials. Also an almost complete utilization of heat is had by the specic arrangement of the process steps. The process steps are arranged according to diminishing heat requirements thus affording greater economy of operation.

Although this process has been described in terms of its preferred modications, it is understood that Various changes may be made without departing from the spirit and scope of the disclosure of the claims.

I claim:

l. A process for the use of spent Fischer- Tropsch catalyst selected from the group consisting of iron, cobalt, and nickel and spent oxygen donor selected from a group consisting of the oxides of iron, cobalt and nickel from a Fischer- Tropsch synthesis gas producing process capable of acting as a Fischer-Tropsch hydrocarbon synthesis catalyst when in a reduced state, which comprises passing said spent Fischer-Tropsch hydrocarbon synthesis catalyst in admixture with said spent oxygen donor from a Fischer-Tropsch synthesis gas producing process at a temperature of 1400 to 2000 F. to steam decarbonization and regeneration, contacting the mixture with steam and hydrogen at a temperature of 1100 to 1250 F. and thereby removing all of the carbon and waxes deposited on said spent catalyst and partially oxidizing said spent catalyst and said spent oxygen donor, passing the partially oxidized material at a temperature of 1100 to 1250 F. in contact with steam and thereby more fully oxdizing said material and cooling same to a ytemperature of 800 to 950 F., passing at least a portion of the more i'ully oxidized material to regeneration and preheat where it is contacted with a hot gas containing excess oxygen and is completely oxidized and heated to a temperature in the range of 2300 to 2800 F., contacting thus heated and oxidized material as an oxygen donor with natural gas and thereby converting said gas to carbon monoxide and hydrogen by partial oxidation at a temperature of 21500 to'2000 F., and reducing the remain-" ingportion of said more' fully oxidized materiali '5 and using the same as a catalyst in a Fischer- Tropsch synthesisof hydrocarbons.

2. A process according to claim 1 wherein said spenty oxygen donor is passed to said Fischerf Tropsch synthesis of hydrocarbons as additional catalystthereoi".v y

3. A process according to claim 1 whereinl said terial is superheated by contacting the decar-F bonized material forv decarbonization of other spent material. y

5. A process according to claim l wherein tlie natural gas partial oxidation products are passed to said Fischer-Tropsch synthesis of hydrocarbons.

6. A process according to claim 1 wherein the hydrogen and carbon monoxide produced by the decarbonization and partial oxidation of said spent Fischer-Tropsch catalyst is passed to said Fischer-Tropsch synthesis of hydrocarbons.

7. A process for the use of spent Fischer- Tropsch catalyst selected from the group consisting of iron, cobalt, and nickel and spent oxygen donor selected from the group consisting of the oxides of ironfcobalt, and nickel from a Fischer- Tropsch synthesis gas producing process capable of acting as a Fischer-Tropsch hydrocarbon synthesis catalyst when in a reduced state, which comprises passing a mixture containing said spent Fischer-Tropsch hydrocarbon synthesis catalyst and said spent oxygen donor from a Fischer- Tropsch synthesis gas producing process to steam decarbonization and regeneration, contacting said mixture with steam and hydrogen and thereby removing all of the carbon and waxes deposited on said catalyst and partially oxidizing said catalyst and said oxygen donor, said spent oxygen donor carrying suiilcient heat from the synthesis gas producing process to the decarbonization and regeneration to cause decarbonization and oxidation of said mixture, completely oxidizing and preheating at least a portion of the resulting mixture by contacting same with hot gases containing an excess of oxygen, utilizing said hot oxidized material as an oxygen donor and heat supplier in a Fischer-Tropsch synthesis gas producing step, and reducing the remaining portion of the resulting mixture and using same as a catalyst in a Fischer-Tropsch synthesis reaction.

8. A process for the use of spent Fischer- Tropsch reduced iron oxide catalyst and spent iron oxide oxygen donor from a Fischer-Tropsch synthesis gas producing process capable of acting as a Fischer-Tropsch hydrocarbon synthesis catalyst when in a reduced state, which comprises passing deactivated reduced iron oxide catalyst from a Fischer-Tropsch hydrocarbon synthesis reaction in admixture with spent iron oxide at a temperature of 1600 F. used as an oxygen donor in a Fischer-Tropsch synthesis gas producing'process to steam decarbonization and regeneration, contacting the mixture with superheated steam and hydrogen at a temperature of 1150 to 1200 F. and thereby removing all of the carbon and waxes deposited on said spent catalyst as carbon oxidesI steam, and hydrogen and partially oxidizing said spent catalyst and said spent oxygen donor, heat for this treatment being supplied from the spent oxygen donor, passing the resulting partially ox- 7 idimaenialgeits@ temperature; ots-1 150 150420021" F'f'1in1Q0I-lf=ictwith;freslrsteam.L and V ',thereby,. more n;

fully; OXxiZ-ngi said l f partially `oxidizeo'li material.. A

and cooling sameitda .temperature ofi 85e to 19551 t-ionfof: thefmore; fullyr'rpxidized iron; ,amd-L passing produced by partial oxidation of saidmatulakgasi; andsssinge;'prtionofopgntroxygenidonor from c tmgathegresultingiron;oxidewithmatuml;io f

said naturalgaspartiazkoxidationto.said ilischer.4 Tropsch synthesis of hydrocanbonsgas "desired,v and-.1v treating Vspent Fischer-*Tropsch :cata1yst.and,-f,; spent oxygen-donor as .hereinbeiore described.V Passing@ :pQrtiQnioE-:therfmore fully` oxidized materiali@ regrierationiand; preheanwhere iisfzisxi.v

BERTRANDTJ r l REFERENCES? CITEDJ The fOOWng' l'eferences eremreeordin thee.- iieofthis -peitenti UNITED STATESTATENTS Y 

1. A PROCESS FOR THE USE OF SPENT FISCHERTROPSCH CATALYST SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT, AND NICKEL AND SPENT OXYGEN DONOR SELECTED FROM THE GROUP CONSISTING OF THE OXIDES OF IRON, COBALT AND NICKEL FROM A FISCHERTROPSCH SYNTHESIS GAS PRODUCING PROCESS CAPABLE OF ACTING AS A FISCHER-TROPSCH HYDROCARBON SYNTHESIS CATALYST WHEN IN A REDUCED STATE, WHICH COMPRISES PASSING SAID SPENT FISCHER-TROPSCH HYDROCARBON SYNTHESIS CATALYST IN ADMIXTURE WITH SAID SPENT OXYGEN DONOR FROM A FISCHER-TROPSCH SYNTHESIS GAS PRODUCING PROCESS AT A TEMPERATURE OF 1400 TO 2000* F. TO STEAM DECARBONIZATION AND REGENERATION, CONTACTING THE MIXTURE WITH STREAM AND HYDROGEN AT A TEMPERATURE OF 1100 TO 1250* F. AND THEREBY REMOVING ALL OF THE CARBON AND WAXES DEPOSITED ON SAID SPENT CATALYST AND PARTIALLY OXIDIZING SAID SPENT CATALYST AND SAID SPENT OXYGEN DONOR, PASSING THE PARTIALLY OXIDIZED MATERIAL AT A TEMPERATURE OF 1100 TO 1250* F. IN CONTACT WITH STREAM AND THEREBY MORE FULLY OXIDIZING SAID MATERIAL AND COOLING SAME TO A TEMPERATURE OF 800 TO 950* F., PASSING AT LEAST A PORTION OF THE MORE FULLY OXIDIZED MATERIAL TO REGENERATION AND PREHEAT WHERE IT IS CONTACTED WITH A HOT GAS CONTAINING EXCESS OXYGEN AND IS COMPLETELY OXIDIZED AND HEATED TO A TEMPERATURE IN THE RANGE OF 800 TO 2800* F., CONTACTING THUS HEATED AND OXIDIZED MATERIAL AS AN OXYGEN DONOR WITH NATURAL GAS AND THEREBY CONVERTING SAID GAS TO CARBON MONOXIDE AND HYDROGEN BY PARTIAL OXIDATION AT A TEMPERATURE OF 1500 TO 2000* F., AND REDUCING THE REMAINING PORTION OF SAID MORE FULLY OXIZIDED MATERIAL AND USING THE SAME AS A CATALYST IN A FISCHERTROPSCH SYNTHESIS OF HYDROCARBONS. 